With millions of mobile apps available across the globe’s many app stores, it’s getting more and more expensive for developers to effectively market their apps to mobile audiences.

According to the latest data from Fiksu, the cost to acquire a loyal user, or one that opens an app three times, grew from $1.30 in 2012 to $1.62 last year.

“Meanwhile, app downloads over 2013 broke records, though the download growth has been slowing, as previous reports have pointed out, indicating that some maturer markets are nearing their saturation point,” writes Sarah Perez of TechCrunch.

While the percentage slowdown may be accurate this year, it’s based on a larger and ever-increasing raw number of total downloads. In December 2013, for example, the company has been predicting somewhere between 6.6 million and 7 million daily downloads on its own Competitive Index.

Perez believes this “steady overall growth” of app marketing and user acquisition costs may be cause for concern.

“For consumers,” she concludes, “this means in 2014, we might see more of the newer, younger companies trying darker shades of “growth hacking” as a way to find initial traction. Be warned.”